Gas blast circuit breaker



May 9, 1950 R. LUDWIG ET AL 2,507,210

GAS BLAST CIRCUIT BREAKER Filed Nov. 28, 1944 5 Sheets-Sheet 3 a H B E H E U J 7 w M 39 7 l 35 /e l6 1 z? l8 6 $2 I I ,25 70 HIGH TO l/lG/f met-James Jouecr P3556034" 600/864 WITNESSES: INVENTORS May 9, 1950 L R. LUDWIG ET AL GAS BLAST cmcun BREAKER 5 Sheets-Sheet 4 F1.- ed Nov. 28, 1944 W 0 a 0w 5 win n m INVENTORS Ber? am/n EEO/(6F. qa lsa/ ATTORNEY Patented May 9, 1950 GAS BLAST CIRCUIT BREAKER Leon R. Ludwig, Wilkinsburg, and Benjamin P.

Baker, Turtle Creek, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 28, 1944, Serial No. 565,456

34 Claims. I

This invention relates to circuit interrupters, in general, and, more particularly to circuit interrupters which utilize a gas under pressure to eflfect the extinction of one or more arcs drawn within the circuit interrupter.

A general object is to provide an improved circuit interrupter of the gas blast type in which improved mounting constructions are employed to render improved performance with a more safe and rugged construction.

A more specific object is to adapt the dead tank 011 circuit interrupter casing to a circuit interrupter of the compressed gas type in which the casing may in certain instances be pressurized. Preferably, exhaust passages are provided through the bushings which enter the casing and which support on their interior ends arc extinguishing units thus disposed within the casing.

Another object is to provide an improved circuit interrupter which interrupts the three phases of a transmission system and in which are extiguishing units associated with the several poles of the breaker are disposed within a pressurized casing which is preferably a grounded metal tank.

Another object is to provide an improved circuit interrupter of the compressed gas type which is disposed within a grounded metal casing, and in which the cross-bar is used to initiate the opening of the contacts of the arc extinguishing units disposed within the casing. In certain instances, it is advisable to pressurize the casing and to permit the compressed gas to exhaust through bushings extending into the casing and supporting on their interior ends are extinguishing units.

Another object is to provide an improved compressed gas circuit interrupter which is supported within a pressurized casing and to provide improved arc extinguishing units disposed within the casing to more effectively interrupt the electrical circuit passing therethrough.

Another object is to provide an improved circuit interrupter of the compressed gas type in which the arc extinguishing units are disposed in a pressurized casing and in which a blast valve is operated by a cross-bar. After a predetermined movement of the blast valve, the arcing contacts are separated so as to enable the blast of gas to effect the extinction of the are drawn adjacent the arcing contacts.

Further objects and advantages will readily become apparent upon a readin of the following specification taken in conjunction with the drawings; in which:

Figure l is a vertical sectional view taken through a circuit interrupter embodying our invention, the casing not being pressurized, and the contacts being shown in the closed-circuit position;

Fig. 2 is a view similar to that of Fig. 1 in which the casing is pressurized, again the contacts being shown in the closed-circuit position;

Fig. 3 is a vertical sectional view through a circuit interrupter embodying our invention,-the casing being pressurized and the arc extinguishing units being of improved construction;

Fig. 4 is a view similar to Fig. 3 but showing a modified type of arc extinguishing unit;

Fig. 5 is a modified type of compressed gas clr cuit interrupter emodying our invention, the contacts being shown in the closed-circuit position and the arc extinguishing units being of modi-. fled construction;

Fig. 6 is an enlarged view of the right-hand arc extinguishing unit of Fig. 5, the contacts being shown in the partially open circuit position;

Fig. 7 is a modified type of compressed gas circuit interrupter embodying our invention, the arc extinguishing units being of a modified construction;

Fig. 8 is a plan view of the circuit interrupter. shown in Fig. 9;

Fig. 9 is a vertical sectional view of the circuit interrupter shown in Fig. 8 taken along the line IXIX of Fig. 8, the contacts being shown in the closed-circuit position; and

Fig. 10 is a sectional view taken along the line XX of Fig. 9.

In the circuit interrupter of our inventionwe propose to incorporate advantages which have heretofore been found only in conventional dead tank high voltage oil circuit breaker. Some of these advantages are as follows:

1. Structural stability; the use of steel to support all the breaker parts.

2. Inherent geometry of the design to place all live parts above reach without adding deliberately to the minimum height of the breaker.

3. Through type current transformers, in conjunction "with the bushings are obtained at very little additional cost.

4. Potential devices may be obtained at very little additional cost.

5. The porcelain insulation is supported so that it is subjected to compression forces only, and may easily be resiliently mounted to withstand shock.

6. Minimum lengths of porcelains protrude from good solid metal supports.

7. In case of servicing, all parts needing attention are inside and protected from the weather.

8. The pole unit operating mechanism is at ground potential, and thus the auxiliary switch may be directly connected.

In our invention we propose to provide an improved compremed gascircuit interrupter using a metal enclosure or casing as shown in Fig. 1 which possesses all the above advantages and more. Referring more particularly to this figure, it will be observed that the reference nu;- meral l designates a casing, in this instance formed of metal, in which the enclosed region 2 is not prmsurized, but is preferably at atmospheric pressure. Supported from the cover 3:0! i? the casing I are bushings 4, 5 which are preferably of the condenser high voltage type.

Supported at the interior ends of thebushings 4, 5 are are extinguishing units generally designated by the reference numeral 6. Exhaust passages T may extendthrough the bushings 6-, 5 which may be utilized-in exhausting'the contamihated compressed gas to theregion exterior of the casing I after said gas has been utilized to lug action of the compression spn'ng 2|. This draws an are between the upper end of the contact l8 and the stationary contact H, which are guished by a blast of compressed gas downwardly through the conduit I4 into the casing and outwardly to the region exterior of the casing I through the exhaust pas sage 2' provided within the bushing 5.

After the arc is extinguished, further downward movement of the crossar 8 causes a disengagement thereof from the fingers l9 to introduce two isolating gaps into the circuit controlled by the interrupter, the cross-bar finally reaching its full open circuit position as indicated by the 25 ofFig. 1.

In the meantime, the compression spring 2| has retracted. the movable contact III to its closed-circuit position in which it engages the orifice-shaped stationary contact II. To effect a w closing of the interrupter, compressed gas is effect? the eertinction of the are drawnin each unit 8; A cross-bar E electrically connects the two. units- 6 in the closed circuit position of the mtemrpter asshown-by the full lines in Fig. 1.

The cross-bar 8" isreciprocally operated by-an fnsulutlngoperating rod 9 having a piston 10sef? 1 cured'to its. upper end. The piston I0 operates witiiirra piston chamber H having inlet openings l2; l3 associated therewith. It will be-noted that compressed gas enteringthe inlet opening Itydll force thepiston f0; and cross bar'8' downwardi'y'to eflect' the opening: operation of the inferrupter, whereas compressed gas entering the inletopening 13 will force the piston l0 upwardly to thereby eflect the-closing? operation 01" the inten-upter. Other types of pole unitmechanism' may-be used:

An insulating conduit [4 associated with the inletopeni'ng ltisutilizedto' conduct compressed gas to the. two are extinguishing units a during the opening operation.

Each unit 6 comprises a contact foot i5 which is preferably clamped by clamping means It to interior or lower end of the bushing & or 5; The contact foot I! has. an orifice-shaped staflonm'y contact" I I associated-therewith which cooperates with a rod shsped movabie'contactl 8 inthe closed circuit position'as shown.

Secured to the lower end ot'eaclr movablecontact It! is a. pair of resilient fingers f9; which fi-ictionaiirmgage theopposedouter ends oi" the conducting;- cross-bar OF. A' flange- 28'- is rigidly securemto the movable contact: l8 and serves as an upper seatrfor a compression spring' M which biases the movable contact it toward its closedcircuit position. Guide fingers 22 may be provided to guide the movable contact l8 during its reciprocating vertical travel. Preferably, the guide fingers 22 are pivotally mounted at 23 and are spring-biased-inwardiy by suitable means not shown:

During the opening operation compressed gas is admitted by suitable means not shown to theii'rlet opening l2. H'ereit' actstoforce the piston l0 and cross-bar 8 downwardly and also passes dbwnwardlythrougir the conduit Wirrtothe insuiatingicasingflof the unit 8. It will be observed that downward motion of the cross-bar 8 by means of the frictional engagement with theflngers l9 causes downwardopening'movement'of the movable contact ISagainstthe upward blesforced through the inlet 13 to move the piston if and cross-bar 8' upwardly. This effects an: engagement between the opposed outer the cross-bar 5' and the fingers I9 to thereby complete the electrical circuit: through. the: interrupter.

It wi l be observed that in the above mum-- tion, conventional bushing terminals with their current transformers 26 and potential desd'cea 28w may be employed. protruding-tron: thee-tonal! that metal. casing I. Dependingtronz thmlmveirend of each-bushingis the.compressed airihtermmer; The contacts are actuated bya traverse lcslmilmr to that-used in an oil breaker; Theifirstpamot the motion of the-traverse causw the arcingcon-s tacts. to part. By the time the arc.- hambeem eztinguished the. continued motion ot-thetruorsw 8. forms twoisolating air. gaps between thains terrupters the same as in auoil breaker.

Indicating q pment. generally decimated.- hm the reference numeral Emma be employed: hm conjunction with the auxiliary switch 84' twinsdicate both the fully open andzfi'ully closedpositions otthe interrupter. g -1 If the metal enclosure or I! ls.d at atmospheric pressure as described; thereon-.- pressedgas may be talnemtmm asultahlee reservoir, not shown, through: one valves and: through smtahiezgas into the interrupter Atter'passing hollow terminal bushingsfi- 5 asslimm. toithos region. exterior ot'the casing I; a ij It the enclosure or casing I is pressurized as: shown in Fig. 2, the size ai time-entire metre except for the bushings can be some-- what in proportion to the absolute in that the striking distances go down mvemely-withi the pressure. Thepractical limit in strikingdh tances may be assumed as that which isnecesa sary to hold for a short time line to. groundwoltage plus a 25% overshootln voltage it'fotsoma reason the enclosure I lost its pressure At higher pressures the striking distances would be less;

than required by oil.

In our invention the compressed gas or air. for operatin the breaker andinterrupting the: arcmaycome from an external storage-reservoiraw in Fig. 1 and after passing through thearomaw be discharged to atmosphericpressurethrough the hollow terminai bushings 4, 5 or some other passage. But, preferably, itmay betaken (ii,- rectly from the pressurized enclosure or casing,- I as shown in Fig. 2. In this event it will pass 5 through conduits I4 into the units 6 and discharge through the hollow bushing terminals 4, 5 by means of the discharge or exhaust passages 7.

Referring more particularly to Fig. 2 it will be observed that the casing i is pressurized so that the distances between the units 6 and the casing I may be considerably reduced. Also the isolating gap distances may be decreased. By actuating the solenoid 21 by energizing the coil 28, pilot valve 29 may be lowered to permit high pressure gas from the casing I to act on the top side of piston 30 which is secured to the upper end of the stem 3! of blast valve 32. The opening of the blast valve 32 permits high rpressure gas from the casing I to flow past the valve seat 33 into the region 34. Here it both acts on the top face of the piston I and through the conduit is leading to the two units 5. The opening operation of the interrupters is the same as previously described; consequently, a further description thereof appears unnecessary. Again the exhaust gas is discharged from the casing I through the exhaust messages I provided in the bushings 4, 5.

The arc extinguishing units may be of the type shown in Figs. 1 or 2 or transverse splitters 35 may be employed as shown in Fig. 3.

In Fig. 3 a modified type of arc extinguishing unit, generally designated by the reference numeral 38. is employed. A rod-shaped movable contact 31 is secured by drictional engagement to the outer end of the cross-bar a and coo erates with a flat leaf-shaped stationary contact 38, the latter terminating at its right-hand end with a conducting tube 39 which passes through the bushing 5.

Consequently, during the opening operation, an' arc is drawn between the upper end of the movable contact 31 and the stationary contact 38 past the horizontally disposed insulating splitters 35. The blast of compressed gas passing downwardly through the conduit I l initiated by the same means as was described in connection with Fig. 2, forces the are against the splitters 35 to effect the extinction thereof. The exhaust gases pass upwardly out of the casing I through theexhaust passage: 1.

From the above operation, it will be apparent that following separation between the ends of the ores-bar 8 and the fingers is secured to the movable rod-shaped contact 31, two isolating gaps in the circuit are thereby provided and the compression spring 2| serves as in the prior embodimenisof our invention to effect a retraction of the movable contact 31 to its closed position in which it engages the strap 38. Consequently, the cross-bar 8 moves downwardly to the position indicatcd by the dotted lines 25.

It will be observed that the arc extinguishing imit 38 is composed entirely of insulating material 'with the except on oi the strap 38. Also it' will be observed that the cross-bar 8 continues its downward movement to the position indicated by the dotted lines 25 in Fig. 3 to effect two isolating gaps in the circuit. The operating arrangement is the same as previously described in connection with Fig. 2.

In Fig. 4 a modified type of arc extinguishing unit 40 is employed having gas-evolving insulating means 4| defining a passage 42 of cylindrical shape through which the movable contact IB may be drawn during the opening operation. Again a compression spring 2! biases the contact [8 toward its closed position and fingers I9 frictionally engage the cross-bar 8 during a portion of the latters opening travel. The operating ar- 6 rangement may be the same as described in connection with Figs. 2 and 3.

During the opening operation, opening of the blast valve 32 permits the compressed gas or air within the casing I to force the piston Ill and cross-bar 8 downwardly. Also compressed gas flows downwardly through the conduit I4 into the unit 40. The downward motion of cross-bar 8 making frictional engagement with the fingers I9 forces the movable contact l8 downwardly away from the stationary contact i1 against the upward biasing action exerted by the compression spring 2|. The are thus drawn between the contacts ll, I8 is drawn through the cylindrical passage 42. Within this passage the arc causes the evolution of gas from the insulating material lining the walls of the passage 42 which assists high current interruption.

The advantages thus gained by the foregoing constructions are as follows:

1. We have provided a smaller, cheaper and more rugged construction than the conventional outdoor compressed air circuit interrupter.

2. An enclosure comparable to the conventiona1 0L1 breaker is made possible by the high dielectric strength of fluid under pressure.

3. An inside isolating gap as short as that in an oil circuit breaker may be employed which is only a small fraction of the length required by conventional air circuit breakers.

4. A direct connection for the auxiliary switch operating mechanism may be provided.

5. Higher speed interruption, isolation and reclosing is made possible by decreased dimensions, resulting from all live parts operating in a high pressure, clean, dry atmosphere; I

6. Cheaper current transformers and potential devices may be employed.

7. Porcelain insulation may be employed which is better supported than heretofore and is placed in compression.

In order to obtain high speed interruption. it is necessary to place the blast valve as close to the interrupter as possible so that very little or no timewillberequiredtofilltheairpassagebetween the blast valve and the interrupter. The constructions shown in Figs. 5 and 7 are such that little time is required for the air to reach the interrupting orifices. Referring to Fig. 5 it will be observed that a blast valve 43 has a portion 44 constituting a Piston surface. The blast valve 3 slidably operates within a. chamber 45 supported by suitable means not shown from the wall of the casing l. The cross-bar 8 during its downward movement frictionally engages fingers I 9 disposed at the lower end or a stem 45 having secured thereto at the upper end thereof a pilot valve 41 closing-an opening 48 in the blast valve 43. A compression spring 48 biases the pilot valve ll upwardly toward its closed position.

Consequently. the initial downward movement of the stem 45, caused by the frictional engagement between the fingers I 9 and the cross-bar B, discharges the compressed gas within the region 50 through the opening 48, through the tubular movable contact 5! and through the exhaust passage 1 to the region exterior or the casing I. This dumping of the air below the blast valve 43 by operation of the pilot valve 4] permits the high pressure gas within the casing I to act on the pisston surface 44 forcing the blast valve 43 downwardly.

After a predetermined downward movement of the blast valve 43, the inwardly extending portion 52 thereof strikes a flan e 53 integrally f rm d with the movable contact 5i to cause downward movement'of the movable contact an arc between the contacts 55, l? which is extinguished by a flow of compressed. gas passing past the'blast valve 43 and-out of the buslnng 5 through the exhaust passage 1:

fiontinued downward movement of the crossbar 8- causes a disengagement thereof from the fingers- 19; This creates two isolating disconnect wpsdmthe circuit and permits the compression springsmc, Manda; to efiecta retraction of the movable parts of the modified arc extinguishing unit 55-. The hleedcr opening 56 provided in' the chamber fit'rpermits high pressure sasto leak from theorising i into the region 58 below the blast valvei.

Conmuently, in this modification of our invacation, we have provided means for omitting the conduit 24 and for providing a very short distance between: thesect of the blast valve and the interrupting orifice.

Figndshows in a more clear manner the initial opening: movement of the movable parts of the arc extinguishing unit 55.

Themodified type of arc extinguishing unit 51 aseshown in Fig. 7 operates in a manner somewhat similar to that previously described in connationwith Figs. 5 and 6. The: unit 51 compnisesare insulating; casing 58 having a guide spider Q disposed therein which serves to guide the vertical reciprocating motion of a movable contact Elli biasedupwardly by a compression spring GI. Again the cross-bar B initially oper m by!- irictional engagement a pilot valve 41 whinh nonnally closes on opening 63 provided in flieiblast valve; The blast valve 43 is biased against its seat 62- by a compression spring 63. muting the opening operation the cross-bar 8 moves downwardly causing opening of the pilot value I?! thus dumping the air below the blast valve 43: The high pressure gas within the casin: l acts on the surface area 41!; through the apertln'es 64 provided in the casing 65 to force the-blast valve 43-downwardly against the upward :act'ionexerted by the compression spring Afters predetermined downward travel of the blast valve 03 the inwardly extending portion 68 thm eofi strikes-the flange 61 secured to the movablezoontact 60 causing opening motion of the same; thereby drawing an are between the con- M 21, 6d.- Meanwhilethe compressed gas withinthe casing t has passed the seat 62 and has flowed upwardly into the region; 88 adjacent ihscontact structure. Thus when the contact Ell: separates from the' stationary contact I1 to draw: an arc, the high pressure gas now within the reglnn 68 effects the extinction of this arc, the c gas passing upwardly through the exhaust passage '1' and out of the casing I through the bushing 5-.

Further downward movement of the cross-bar 8 (b the position 25' permits the compression springs 63',- BI and 49 to eficct retraction of the movable parts of the unit 51, the bleed'er openitrgSG again permitting h gh pressure gas within thecaslng l to enter'the region 50 below the blast valve-43: Consequently, in the open circuit posiidol! of the interrupter the contacts are closed and the cross-bar 3 provides two isolating gaps il'rthecircuit.

Figs. 8, 9 and illustrate a circuit interrupter embodying our invention in which the three poles oi the breaker, each pole containing two units serially connected, are positioned within the pressurized casing 78. The two units of each This drawspole of the breaker are preferably of the. types designated by the reference numeral 55 of Fig.v 5 and operate inthe same manner. The operating rod H, composed of insulating material, effects a simultaneous downward movement of the three cross-bars 8 associated with the three poles of the breaker as indicated in- Fig. 10; Again the exhaust gases pass through the bushings 4, 5 to the region exterior of the casing 10 An insulating support neck the three cross-bars 8 with the insulating operating rod 1| which is schematically shown to be operated by a winding 13 and asolenoid 14.. If desired insulating cylinders 15 may basemeployed to assist in electrically isolating thesevera] are extinguishing units 55.

From the foregoing description it will be-apparent that in this modification of our invention we have provided an economicaland space saving arrangement inwhioh reduced. dimensions. are possible in the circuit breaker by employing a pressurized casing Ill in which the interrupting. units of the three poles may be placed. By em,- ploying a single casing 10 forthe three poles of the breaker mounting space is reduced, matarial is saved, and-inspection-is facilitated.

From the foregoing description. of several embodiments of our invention, it will be apparent. that we have invented a compressed. gas circuit. interrupter of novel construction which takes ad vantage of all ofthe desirable. reatures of. dead tank 011- circuit breaker mounting constructions. but yet has additional advantages inasmuch as the enclosure or casing may be pressurized to. reduce the dimensions of the interrupter. The: mounting constructions which we' have. shown thus result in economical saving otmaterialrlgld. construction, and yet are such that inspection may be easily permitted. The arceittingukln-- 111g units maybe 0! difl'erent types and although we have shown a few particular lobes,- ibis to. be clearly understood that the scope of our lnvention is broad and is not confined-to thawtlcular type of extingulshingumts which wa'have: described.

Although we have shown and described-specific structures, it is to be clearly understood that the same were merely for the purpose. of illus traticn and that changes-andmodiflcations may readily be made therein by those skilled in the art without departing from the spirit and scope. of the appended claims. A

We cla'm as our invention:-

1. In a circuit interrupter of the compressedl gas-type. a casing. containing gas at substantial- 1y atmospheric pressure, two bushings extendinglnto the casing and having exhaust passages; ex tending therethrough, an arc extin unit disposed adjacent the interior and or. eachbushing, a cross-bar disposed within the casingand. electrically interconnecting the units in theclosed circuit position, a movable contact associated: witheach unit, meansi'or forcing: gas adw Jacent the morable contact of each unit, valve means other. than the movable contacts for controlling the flow at gas. thecross-har causing. tha openlngmovementof the movable contact during the initial portion of its opening, travell and. means for. reclosing the contacts alter the cross,- bar has established the isolating gaps.

2- In a compressed gas circuit interrupter, a casing, a bushing extending into the casing and having an exhaust passage extending therethrcugh. an arc extinguishing unit disposed ad jacent the interior end of. the bushing, 21 star 12 structurally intercontlonary orifice-shaped contact, a movable contact cooperable with the stationary contact to establish an arc, a cross bar, means biasing the movable contact toward its closed circuit position. a conduit for compressed gas leading into the unit. valve means other than the movable contact for controlling the flow of gas through the conduit, and the initial opening movement of the cross-bar causing opening movement of the movable contact.

3. In a circuit interrupter of the compressed gas type, a casing containing gas at substantially atmospheric pressure, two bushings leading into the casing and having exhaust passages extending therethrough, each bushing supporting adjacent its interior end an arc extinguishing unit, a cross-bar, a stationary orifice-shaped contact and a. movable contact associated with each unit, means biasing each movable contact toward its closed position against the stationary contact, a conduit for conducting compressed gas into the two units, valve means other than the movable contacts for controlling the flow of gas through the conduit, the cross-bar causing the opening movement of both movable contacts during the initial opening movement 01 the crossbar. and the cross-bar subsequently introducing two isolating gaps into the circuit controlled by the interrupter.

4. In a compressed gas circuit interrupter, a casing containing gas under pressure, two bushings extending into the casing and having exhaust passages leading therethrough, an are extinguishing unit supported adjacent the interior end of each bushing, a cross-bar, a movable contact associated with each unit. means whereby the initial opening movement of the cross-bar causes the opening movement of each movable contact associated with each unit, said last-mentioned means also causing reclosure of the contacts of each unit after establishment of the isolating ps by the cross-bar, and valve means other than the movable contacts for controlling the flow of gas adjacent a movable contact.

5. In a compressed gas circuit interrupter, a casing containing gas under pressure, two bush- 11138 extending into the casing and having exhaust passages leading therethrough, a substantially enclosed arc extinguishing unit supported adiacent the interior end of each bushing, a cross-bar, a movable contact associated with each unit, and the initial opening movement 01' the cross-bar causing the opening movement of each movable contact associated with each unit, a stationary orifice-shaped contact associated with each unit, means biasing each movable contact toward its respective stationary contact, and valve means other than the movable contacts for controlling the flow of gas from the casing through the two orifice-shaped contacts.

6. In a circuit interrupter oi the compressed gas type. a casing containin gas under pressure, six bushings extending into the casing having ex haust passages extending therethrough, an arc extinguishing unit disposed adjacent the interior end each bushing, a conducting cross bar electrically interconnecting two units of each pole of the interrupter, and means for simultaneously operating the three cross-bars, contact structure disposed within each unit, and the initial opening movement of the cross-bar for each pole causing opening movement of the contact structure for the two units associated with that pole.

T. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, a bushing extending into the casing and having an exhaust passage extending therethrough, an arc extinguishing unit disposed adjacent the interior end of the bushing, means of gas evolving material defining a cylindrical passage within the unit and in communication with the aforesaid exhaust passage, means for drawing an are within the unit through the cylindrical passage, and valve means other than said last-mentioned means for controlling the flow of gas from within the casing through the cylindrical passage to exhaust out through the bushing.

8. In a circuit interrupter of the gas blast type, a. casing containin gas under pressure. a bushing extending into the casing and having an exhaust passage therethrough, an arc extinguishing unit disposed adjacent the interior end of the bushing, a blast valve, 9. pilot valve, a cross-bar, the initial opening movement of the cross-bar operating the pilot valve to cause a dumping of gas in back of the blast valve.

9. In a circuit interrupter of the gas blast type, a casing containing gas under pressure, a bushing extending into the casing and having an exhaust passage therethrough, an arc extinguishing unit disposed adjacent the interior and of the bushing, a blast valve, a pilot valve, a cross-bar, the initial opening movement of the cross-bar operating the pilot valve to cause a dumping of gas in back 01' the blast valve, a. movable tubular contact through which the gas is dumped, and the blast valve opening the movable contact after a predetermined opening travel.

10. In a circuit interrupter of the gas blast type,

a casing containing gas under pressure. a bushing extending into the casing and having an exhaust passage therethroush. an arc extinguishing unit disposed adjacent the interior end of.

the bushing, a blast valve. a pilot valve, a crossbar. the initial opening movement of the crossbar operating the pilot valve to cause a dumping of gas in back or the blast valve. an orifice-shapedstationary contact. a movable rod-shaped contact, and the blast valve opening the movable contact after a predetermined opening travel 01' the blast valve.

11. In a circuit interrupter oi the compressed gas vn .acasing,apairotbushingsextending into the casing and having arc extinguishing units disposed adjacent their interior ends, a conducting cross-bar for electrically interconnecflng the units in the closed circuit position of the interrupter. contact structure associated with each unit to establish an arc, valve means other than the contact structure to control the flow of gas adjacent the arc, and means whereby the crossbar causes initial opening of the contact structure to establish arcing and permits reclosure of the contact structure while the cross-bar continues its opening movement to insert two isolating gaps in the circuit. a

12. In a circuit interrupter of the compressed gas t pe. a casing containing gas under pressure, a pair of bushings extending into the casing and having arc extinguishing units disposed adjacent their interior ends, a conducting cross-bar for electrically interconnecting the units in the closed circuit position of the interrupter, contact structure associated with each unit to establish an arc, valve means other than the contact structure to control the flow of gas adjacent the arc. and means whereby the cross-bar causes initial opening of the contact structure to establish arcing and permits reclosure of the contact structure while the cross-bar continues its opening movement to insert two isolating gaps in the circuit.

13. In a circuit interrupter, a casing, two bush- 11 lugs extending within tze casing and having arc extinguishing units disposed adjacent their interior ends, contact structure associated with each unit biased to the closed circuit position, a conductin cross-bar electrically interconnectin the two units n the closed circuit position of the interrupter, momentary engaging means for permitting initial opening motion of the cross-bar to cause initial separation of the contact structure of each unit, the contact structure reclosing following extinction of the arcs, and the continued opening motion of the cross-bar inserting two isolating gaps in the circuit.

14. In a circuit interrupter, a casing containing gasunder pressure, two bushings extending within the casing and having arc extinguishing units disposed adjacent their interior ends, contact structure associated with. each unit biased to the closed circuit position, a conducting cross-bar electrically interconnecting the two units in the closed circuit position of the interrupter, momentary engaging means for permitting initial opening motion of the cross-bar to cause initial separation of the contact structure of each unit, the contact structure reclosing following extinctip; of the arcs, and the continued openin motion of the cross-bar inserting two isolating gaps in the circuit.

15. In a circuit interrupter of the compressed gas a casing containing gas under pressure, a bushing extending into the casing and having an arc extinguishing unit disposed adjacent its interior end, contact structure including an oriflee-shaped stationary contact and a movable contact separable from the stationary contact to establish an arc, an annular blast valve surrounding the movable contact and making abut g engagement with the stationary contact, and dlstnnnect means or causing operation of the blast valve prior to contact separation and maklng only momentary engagement therewith.

, 16. In a circuit interrupter of the compressed gas type. a casing con aining gas under prmsure, a bushing extending into the casing and having an .arc extinguishing unit disposed adjacent its interior end, contact structure including an oriilca-shaped stationary contact and a movable contact separable from the stationary contact .to

an arc. an annular blast valve surroundin; the movable contact and making abutting eneasement with the stationary contact, di connept means for causing operation of the blast valve, and a lost-motion connection between the blast valve and the movable contact 17. In a. circuit interrupter oi the compressed end, contact structure including an oritlcershaped stationary contact and a movable contact separable from the stationary contact to establish an are, an annular blast valve surrounding the movable contact and making abutting engagement with the stationary contact, a pilot valve, and the disconnect means causing operatipn of the pilot valve.

.18. In a circuit interrupter oi the compressed g 8.s type, a casing containing gas under pressure. a bushing extending into the casin and having an arc extinguishing unit disposed adjacent its interior end. contact structure including an orilice-shaped stationary contact and a movable contact separable from the stationary contact to establish an arc, an annular blast valve surrounding the movable Contact and making abutting engagement with the stationary Contact, a. pilot valve, the disconnect means causing operatio'ndf the pilot valve, and a lost-motion connection between the blast valve and the movable contact.

19. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, an arc extinguishing unit disposed within the casing, movable contact structure separable to establish an are, a blast valve, disconnect means operable to cause opening of the blast valve, and a lost-motion mechanical connection betweep'the blast valve and the movable contact structure.

20. In a. circuit interrupter of the compressed gas type, a casing containing gas under pressure, an arc extinguishing unit disposed within the casing, a stationary contact cooperable with a movable contact to establish an arc, a blast valve for admitting gas within the casing toward the stationary contact prior to contact separation. disconnect means. and the disconnect means causing operation of the blast valve and making only momentary engagement therewith.

21. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, an arc extinguishing unit disposed within the casing. a stationary contact cooperable with a movable contact to establish an arc, a blast valve for admitting gas within the casing toward the stationary contact, a pilot valve for dumping gas below the blast valve. disconnect means. and the disconnect means causing operation of the pilot valve and making only momentary engagement therewith.

22. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure. a bushing extending within the casing and harving an exhaust passage therethrougb, an are exunit disposed within the casing adjacent the interior end of the bushing, an or!- flee-shaped stationary contact cooperable with 'a movable contact to establish an are, .a blast valve for admitting gas within the casing toward the stationary contact prior to contact separation, disconnect means, and the disconnect means causing operation r the blast valve and making only momentary engagement therewith.

23. In a circuit interrupter of the compressed gas type, a casing containing gas under'pressure, a bushing extending withlnthe casing and having an exhaust passage therethrough. an are exg unit disposed within the casing adlacent the interior end of the bushing, an oriflee-shaped stationary contact cooperable with a movable contact to establish an arc, a blast valve for admitting gas Within the casing toward the stationary contact and out the bushing, a pilot valve for dumping gas below the blast valve, disconnect means, and the disconnect means canslog operation of the pilot valve.

24. In a circuit interrupter of the compressed gas type, a casing, a pair of bushings extending into the casing and having arc extinguishing units disposed adjacent their interior ends, at least one of the bushings having an exhaust passage extending therethrough, a conducting crossbar for electrically interconnecting the units in the closed circuit position of the interrupter, contact structure associated with each unit to establish an arc, valve means other than the contact structure to control the flow of gas adjacent the arc, the exhaust gas for at least one of said are extinguishing units exhausting through the bushing having an exhaust passage extending therethrough, and means whereby the cross-bar causes initial opening of the contact structure to establish arcing and permits reclosure of the contact structure while the cross-bar continues its opcn- 13 ing movement to insert two isolating gaps in the circuit.

25. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, a pair of bushings extending into the casing and having arc extinguishing units disposed adjacent their interior ends, at least one of the bushings having an exhaust passage extending therethrough, a conducting cross-bar for electrically interconnecting the units in the closed circuit position of the interrupter, contact structure associated with each unit to establish an arc. valve means other than the contact structure to control the flow of gas adjacent the arc, the exhaust gas for at least one of said are extinguishing units exhausting through the bushing having an exhaust passage extending therethrough, and means whereby the cross-bar causes initial opening of the contact structure to establish arcing and permits reclosure of the contact structure while the cross-bar continues its opening movement to insert two isolating gaps in the circuit.

26. In a circuit interrupter, a casing, two bushings extending within the casing and having arc extinguishing units disposed adjacent their interior ends, at least one oi the bushings having an exhaust passage extending therethrough, contact structure associated with each unit biased to the closed circuit position, a conducting crossbar electrically interconnecting the two units in the closed circuit position of the interrupter, momentary engaging means for permitting initial opening motion of the crossbar to cause initial separation of the contact structure of each unit, the contact structure reclosing following extinction of the arcs, and the continued opening motion of the cross-bar inserting two isolating gaps in the circuit.

27. In a circuit interrupter, a casing containing gas under pressure, two bushings extending within the casing and having arc extinguishing units disposed adjacent their interior ends, at least one of the bushings having an exhaust passage extending therethrough. contact structure associated with each unit biased to the closed circuit position, a conducting cross-bar electrically interconnecting the two units in the closed circuit position of the interrupter, momentary engaging means for permitting initial opening motion of the cross-bar to cause initial separation of the contact structure of each unit, the contact structure reclosing following extinction of the arcs, and the continued opening motion of the crossbar inserting two isolating gaps in the circuit.

28. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, a. bushing extending into the casing and having an arc extinguishing unit disposed adjacent its interior end, said bushing having an exhaust passage extending therethrough, contact structure including an orifice-shaped stationary contact and a movable contact separable from the stationary contact to establish an arc, an annular blast valve surrounding the movable contact and making abutting engagement with the stationary contact, disconnect means for causing operation of the blast valve prior to contact separation and making only momentary engagement therewith, and the blast of gas causing extinction of the arc exhausting out of the casing through the exhaust passage extending through said bushing.

29. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, a bushing extending into the casing and having an arc extinguishing unit disposed adjacent its interior end, said bushing having an exhaust passage extending therethrough, contact structure including an orifice-shaped stationary contact and a movable contact separable from the stationary contact to establish an are, an annular blast valve surrounding the movable contact and making abutting engagement with the stationary contact, disconnect means for causing operation of the blast valve, a lost-motion connection between the blast valve and the movable contact, and the blast of compressed gas causing extinction of the arc exhausting out of the casing through the exhaust passage extending through said bushing.

30. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, a bushing extending into the casing and having an arc extinguishing unit disposed adjacent its interior end, said bushing having an exhaust passage extending therethrough, contact structure including an orifice-shaped stationary contact and a movable contact separable from the stationary contact to establish an arc, an annular blast valve surrounding the movable contact and making abutting engagement with the stationary contact, a pilot valve, the disconnect means causing operation of the pilot valve, the blast of compressed gas causing extinction of the arc exhausting out of the casing through said exhaust passage extending through the bushing.

31. In a circuit interrupter of the compressed gastype, a casing containing gas under pressure. a bushing extending into the casing and having an arc extinguishing unit disposed adjacent its interior end, said bushing having an exhaust passage extending therethrough, contact structure including an orifice-shaped stationary contact and a movable contact separable from the stationary contact to establish an are, an annular blast valve surrounding the movable contact and making abutting engagement with the stationary contact, a pilot valve, the disconnect means causing operation of the ilot valve, a lost-motion connection between the blast valve and the movable contact, and the blast of gas causing extinction of the arc exhausting out of the casing through the exhaust passage extending through said bushing.

32. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, a bushing extending into the casing having an exhaust passage extending therethrough and supporting an arc extinguishing unit within the casing, movable contact structure separable to establish an arc, a blast valve, disconnect means operable to cause opening of the blast valve, a lost-motion mechanical connection between the blast valve and the movable contact structure, and the blast of gas causing extinction of the arc exhausting out of the casing through the exhaust passage extending through said bushing.

33. In a circuit interrupter of the compressed gas type, a casing containing gas under pressure, a bushing extending into the casing and having an exhaust passage extending therethrough, an arc extinguishing unit disposed within the casing and supported by the interior end of the bushing,

a stationary contact cooperable with a movable contact to establish an arc, a blast valve for admitting gas within the casing toward the stationary contact prior to contact separation, disconnect means, the disconnect means causing operation of the blast valve and making only momentary engagement therewith, and the blast of gas causing extinction of the arc exhausting out of the casing through the exhaust passage extendihg th'r'o'ug'h sai'dbushing.

'34. In a circuit interrupter 0'1" the compressed gas type, a casing containing gas under pressure, abushing extending within the casing an-:1 havmg an exhaust passage extending therethrough, an arc extinguishing unit disposed within the "oa'mgand supported therein by the interior and -toward the stationary contact, "dumping gas below the blast valve, disconnect means, the disconnect means causing operation 01' the pilot valve and making "only momentary e agement therewith, and the blast of gas causin'g extinction of the arc exhausting 'outof the casing through the exhaust passage extending throughsaid bushing.

a iz-iiot valve for LEONYR. LUDWIG. BENJAMIN :P. BAKER.

The following references are 1&6 EREFERENGES CITED of record in {the file of this potent:

UNITED STATES PATENTS Number Name Date 1534,6532 Greenwood Mar. 3, 1.93.1 1;914,8T5 Whitney-at v22.1. June 20,-L933 :1;,965:,551 Koplinwitsch Jul y.3,=1934 22,6849?!) 'slepian June 22,7193? $2,188,382 Leeds .et a]. Nov. 29,1938 2,112,225 Sohofialdzat a]. Bept. 5,.- B3;9 260,188 Oct. 21, 1-941 @62516 Rrinee Nov. 11, 1-944 2,284,842 Prince et a]. June 2.1%? 2,287,5'18 SFhflmim set 111. June 23,1942 

